Mg has specific gravity (density g/cm3, 20° C.) of 1.74 and is the lightest in all metal materials that are used for a structure. Also, Mg has high electric conductivity and vibration absorbing characteristic and thus can be expected as a light-weight material for use in various fields which require these characteristics. Recently, with development of wrought alloys such as a rolled material or an extruded material made of a magnesium-based alloy the major component of which is the above-mentioned Mg, the necessity of welding such wrought alloy has been increasing. As the welding wire made of a magnesium-based alloy, there is known a welding wire which is disclosed in the patent reference 1. This welding wire is manufactured by drawing an extruded material.    [Patent Reference 1]    Japanese Patent No. 3592310, paragraphs 0087, 0091